W3C home > Mailing lists > Public > public-html-a11y@w3.org > February 2010

Re: [media] Moving forward with captions / subtitles

From: Philip Jägenstedt <philipj@opera.com>
Date: Mon, 15 Feb 2010 15:06:07 +0800
To: "Silvia Pfeiffer" <silviapfeiffer1@gmail.com>
Cc: "Eric Carlson" <eric.carlson@apple.com>, "HTML Accessibility Task Force" <public-html-a11y@w3.org>
Message-ID: <op.u75p0hvjatwj1d@philip-pc>
On Mon, 15 Feb 2010 14:41:53 +0800, Silvia Pfeiffer  
<silviapfeiffer1@gmail.com> wrote:

> On Mon, Feb 15, 2010 at 4:34 PM, Philip Jägenstedt <philipj@opera.com>  
> wrote:
>> I think we should optimize for the common case and that having any  
>> nesting
>> when there are at most a few tracks (which should be the overwhelming
>> majority of cases) makes the markup less clear. I could live with  
>> optional
>> grouping, e.g. <trackgroup>:
>> Common case:
>> <video>
>>  <track src="captions.srt">
>>  <track src="zimu.srt" lang="zh">
>> </video>
>> Complex case:
>> <video>
>>  <trackgroup role="captions">
>>    <track src="captions.srt">
>>    <!-- lots of tracks -->
>>  </trackgroup>
>>  <trackgroup role="karaoke">
>>    <!-- lots of tracks -->
>>  </trackgroup>
>>  <!-- lots of groups -->
>> </video>
>> <track>s in a <trackgroup> are mutually exclusive while tracks in  
>> different
>> groups are not. This is the only semantics expressed -- grouping doesn't
>> have to be based on role. By default all tracks are mutually exclusive.
> This is exactly replicating what the wiki page already says, except
> with <trackgroup> instead of <track> and with <track> instead of
> <source>. Also, it adds the discussed stand-alone possibility of
> <track> with a @src attribute, which we had already discussed.
> Could we just stick with the naming as we have it at
> http://www.w3.org/WAI/PF/HTML/wiki/Media_TextAssociations ?

I think calling the grouping element <track> is a bad idea when it in fact  
doesn't specify a track but a group of tracks (each track in <source>).

>> lang="" is already inherited,
> Where from? I am confused.

The language of a node in HTML depends on the node itself and all ancestor  
nodes. [1] In other words lang="" is inherited and I'm saying that if one  
motivation for grouping is to save typing then we can let role="" be  
inherited in the same way.

>> perhaps we could do the same for role="" to
>> that either or both can be specified on <trackgroup>?
> That would be an option to add to the stand-alone <track> element ,
> too (again, going back to previously discussed spec).

No, I'm saying that it can be specified on both <track> and <trackgroup>.

> I'm rather confused by this new proposal, when it mostly replicates
> the old one, just with new names. Also, it doesn't reuse <source>
> which I found an advantage of the previous proposal.

We've agreed on the basics for a long time, this is all about finding the  
appropriate markup/structure to express it, isn't it? I find my  
<track><source> suggestion confusing because <track> actually contains  
many tracks. Also, it makes the nesting mandatory, as <source> cannot be  
given as a direct child to <audio>/<video> as that would conflict with the  
resource selection algorithm. <trackgroup><track> is intended to address  
both of these problems.


Philip Jägenstedt
Core Developer
Opera Software
Received on Monday, 15 February 2010 07:06:53 UTC

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